X-ray thickness gauge



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Aug. 28, 1951 w. N. LUNDAHL XLRAY THICKNESS GAUGE 4 Sheets-Sheet 2 Filed April 28 1949 f4/rie wf af' ,r-qy zar/5w Aug. 28, 1951 w. N. LUNDAHL X-RAY THICKNESS GAUGE Filed April 28, 1949 ug- 28, 1951 w. N. LUNDAHI. 2,565,734

X-RAY THICKNESS GAUGE Filed April 28, 1949 Y 4 Sheets-Sheet 4 INVENTOR w M l wpa/w j 2 V ATTORNEY Patented ug. 28, 1931 UNITED STATES PATENT OFFICE X-RAY THICKNESS GAUGE Walter N. Lundahl, Pikesville, Md., assgnor t Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April v28, 1949, Serial No. 90,121

(Cl. Z50- 833) y Claims. 1

The present invention relates to X-ray apparatus and more particularly to X-ray thickness gauges.

At the present time X-ray thicknes gauges are being used more and more extensively in industry to measure the thickness of sheet and strip material as it comes from the rolling mill. Such gauges make use of the long known phenomenon that the absorption of monochromatic X-rays by a homogeneous material varies, among other things, with the thickness of such material. Accordingly, the common practice is to measure the intensity of an X-ray beam passed through a material of preselected thickness and to compare such intensity with that of an X-ray beam passed through the same material which is being gauged. By the use of a null meter, a zero reading is obtained so long as the thickness of the gauged material is equal to that of A the selected standard while any variation is immedately registeerd by a deilection of the meter from zero. Some X-ray thickness gauges employ but a single X-ray tube emitting a beam in two directions while the other and preferable system is to utilize two X-ray tubes but in either case, thickness variations of small magnitude, such as .001 inch, can be readily detected.

Heretofore, one of the disadvantages of one type of X-ray thickness gauge has been the necessity for changing standard thickness samples. This requires the operator to remove the standard thickness sample used in the previous run of material and insert the new standard thickness sample equal to the desired or prime thicknes of the new order of material to be run through the mill, shear or classifiers. After insertion of the new fixed standard sample in its position to be intercepted by the xed standard X-ray beam, a balance sample of the same standard thickness must then be inserted to be intercepted by the other or gauging X- ray beam for the purpose of making a balance check which should thus give a zero reading on the meter. Following this balance check, a standard variable sample, i. e., one of preselected thickness diiierential is then substituted for the balance sample, and the meter reading noted to determine if the system is functioning properly to accurately record this Variation of the variable standard sample from that of the xed standard sample.

These required tests consume considerable time on the part of the operator in inserting the Various samples and walking to and from the control apparatus all of which is lost to time of operation of the high speed rolling mill.

It is accordingly the primary object of the present invention to provide van X-ray thickness gauge which is entirely automatic in its operation to calibrate and check for a desired gauge thickness.

Another object of the present invention is the provision of an .X-ray thickness gauge which is rapidly set automatically in response to initiation by an .operator for calibration and checking so as to record the precise thickness of material coming from a rolling mill.

Another object of the present invention is the provision of an X-ray thickness gauge wherein the operator may automatically set any desired xed standard sample, make a balance check and a standard variation check, entirely from the control stand thus eliminatin-g the necessity of approaching the X-ray generators or the rolling mill.

Still further objects of the present invention will become obvious to those skilled in the art by reference to the accompanying drawings, wherein:

Fig. 1 is a schematic illustration of an X-ray thickness gauge constructed in accordance with the present invention;

Fig. 2 is an elevational View of the turret V-mechanism portion of the X-ray thickness gauge as shown in Fig. 1 with other portions of the gauge .being lschematically shown;

Fig. 3 is a sectional View taken on the line IlI--III of Fig. 2, looking in the direction of the arrows;

Fig. 4 is a sectional View taken on the line IV-IV of Fig. 2, looking in the direction of the arrows;

Fig. 5 is an enlarged fragmentary View of the portions of the turret mechanism as illustrated in Fig. 3 and Fig. 4, together With a schematic showing of a portion of the electrical circuit for operating such portions;

Figs. 6 and 7 are identical to Fig. 5, except that they illustrate different superimposed positions of the two portions of the turret mechanism as shown in Figs. 3 and 4;

Fig. 8 is a cross-sectional View of the turret mechanism portion taken on the line VIII-VIII of Fig. 5;

Fig. 9 is a diagrammatical illustration of the decade selector portion of the X-ray thickness gauge of the present invention as illustrated in Fig. 1, together with portions of the electrical control circuits; and

Fig. is a diagrammatical illustration of the electrical control circuits which together with the portion shown on Fig.'9, constitute the complete electrica1 control circuits for the decade selector.

Referring now to the drawings in detail, the embodiment of the X-ray thickness gauge of the present invention, as shown in Fig. 1, comprises a source of X-rays 5, such as an X-ray tube 2 (Fig. 2) housed within a shock-proof casing, and positioned to project an X-ray beam in a` horizontal plane and a similar source of X-rays 9, positioned to project an X-ray beam from an X-ray tube 3 (Fig. 2) downwardly in a vertical plane which intersects the horizontal beam. At the intersection of these two X-ray beams a pickup 1 is positioned which comprises a fluorescent screen 9 and photomultiplier tube 9 (Fig. 2).

The two sources of X-rays are connected to a tandem X-ray stabilizer unit I0, such as shown in the copending application of Walter N. Lundahl and Robert L. Wright, Serial No. 25,954, filed May 8, 1948, now Patent 2,492,304, assigned to the same assignee as the present invention, in order that the two X-ray sources have a constant ratio of one to one between the intensity of their respective X-ray beams. The pickup 1 is connected to an amplifier and photomultiplier tube stabilizer I2, which in turn is connected to a sensitivity control I3, with the latter being connected to a discriminator and indicator unit I4. A selective control I5 for controlling the rolling mill screw-downs for adjusting the thickness of the rolled material is also connected to the discriminator and indicator I4.

As will also be noted from Fig. l, the thickness gauge is provided with a turret mechanism I5 which includes a pair of horizontally rotatable discs I1 and I8, positioned beneath the material I9 to be gauged as it comes from the rolling mill 2U, with the outer peripheral edge of these discs I1 and IB being disposed so as to intercept the X-ray beam from the source 5. In a similar manner the turret mechanism includes a pair of vertically disposed discs 22 and 23 with their outer peripheral edge positioned to intercept the X-ray beam projected by the source 5. Adjacent the discs I1 and I8 is a flag-gauge 24 operated by a solenoid 25 and movable, as hereinafter described, to intercept the X-ray beam from the source 6 and an identical ag-gauge 2B operated by a solenoid 21 is positioned adjacent the discs 22 and 23 which is movable into a position to intercept the X-ray beam from the source 5. The turret mechanism together with its discs I1, I8, 22 and 23, as well as the solenoids 25 and 21, are connected to a decade selector 28.

From Fig. 1, it will be noted that the decade selector 28 is provided with a face panel on which are mounted a plurality of knobs 29, 39 and 32, and a pair of switch levers 33 and 34. The knob 29 is provided with a pointer registrable with graduations corresponding to thicknesses of one-tenth inches, the knob 39 having a pointer registrable with graduations corresponding to one-hundredth inches, and the pointer of knob 32 being registrable with graduations representing one-thousandths inches. The switch lever 33 has two positions, one registering with an indication representing .001 inches and the other representing .003 inches, while the switch lever 34 has three positions noted as C, R and 2, such switches and knobs being operable for purposes hereinafter described.

As shown in Fig. 2, the turret mechanism I6 is provided with a motor MI connected by a gear train 35 and a hollow shaft 36 to disc 23, and a motor M2 also connected by a gear train 31 and a shaft 38 concentric with shaft 36, to the disc 22. Also a motor M3 is connected through a gear train 39 and a hollow shaft 40 to disc I8 and a further motor M4 is connected through gear train 42 and concentric shaft 43 to disc I1. The shafts 35-38 and 40-43 are journalled, respectively, in suitable bearings 44 and V45. Disposed between the discs 22 and 23 are a pair of discs 49 and 41 of insulating material which are held stationary by a supporting bracket 48. A similar pair of insulating discs 49 and '59 are disposed between the discs I1 and I8 which are likewise prevented from rotation by a supporting bracket 52. Inasmuch as the structure of the discs 22 and 23, as well as the stationary insulating discs 45 and 41, are identical to that of the discs I1 and I8 and their respective stationary insulating discs 49 and 59, a detailed description of one of such pairs should suice.

As shown in Figs. 3 and 8, the rear surface of the metallic disc 22 (as well as the rear surface of metallic disc 23) is provided with a plurality of radially disposed insulating blocks of rectangular conguration 53, each of which are equidistant from the axis of the shaft 38 (the blocks on metallic disc 23 being also equally spaced from the axis of shaft 39), with a single rectangular insulating block 54 of twice the width of the blocks 53, being positioned on a smaller radius from the shaft 38 (and shaft 39 on discs 22). Adjacent the peripheral edge of the metallic discs 22 and 23 they are provided with a plurality of metallic inserts 55 ranging from .O05 to .014 inches thickness in ste-ps of .001 inches plus a N. S. or no sample insert for the disc 22, and ranging from .100 in steps of .0l inches plus a similar N. IS. or no sample insert for the disc 23.

The opposing stationary insulating discs 46 and 41 are provided with a plurality of spring-pressed metallic plunger-contacts 56 of identical number to that of the insulating blocks 53 and the metallic inserts 55 and which are radially spaced to correspond thereto. However, the axial spacing of these plunger-contacts 56 from the shaft 38 (and shaft 39) is made to correspond to that of the larger area insulating block 54 whereas a single spring-pressed contact 51 axially aligns lwith the plurality of insulating blocks 5.1. As can be seen in Figs. 3 and 4, the metallic discs 22 and 23 are electrically grounded, as shown by the respective brush contacts 58 (Fig. 3) and 59 (Fig. 4), while the spring-pressed plunger contacts 55 and 51, carried by the respective stationary insulating discs 49 and 41, are each individually connectedrto `an electrical conductor for a purpose hereinafter described.

Relerring now more particularly to the schematic showing of Figs. 9 and l0, it will be noted that the decade selector control knob 29 rotates a a shaft 59 which in turn operates 9, pair of tandem switches 52 and 63. Each of these switches is provided with a movable contact :arm y(i4 and 95, respectively, which align `with the pointer on the control knob 29 and which engage with a plurality of radially disposed contact buttons 66 and 61, respectively, as desired, by rotation of the shaft 69 and the movable contact arms 64 and carried by such rotatable shaft. In a similar manner, the knob 30 of the decade selector is secured to a rotatable shaft 63 carrying the movable arms B9, 10, 12, 13, 14 and 15 of six tandem switches, each of which has an identical number of radially disposed contact buttons 16, 11, 18, 19, :80 and 82, respectively. The decade selector con-- trol knob 32 is likewise secured to a rotatable shaft -83 with this latter carrying movable arms 84, 85, 86, 81, t8, 83 and 90 of a seven gang tandem switch arrangement with the knob pointer aligning with the movable arms in the same manner as with the two and six gang tandem switch arrangements controlled by knobs 29 and 30. Each switch arm carried by the shaft 83 is movable by an operator to engage one of a plurality of radially disposed contact buttons 95, 91, 58, 95, |00, |02, 03, respectively, making up the seven gang tandem switches. The two position switch 33 of the decade selector rotates a shaft |04 carrying movable arms |05 and |06 of a two gang tandem switch with such arms being engageable with button contacts |01, yand |08, or |09 and H0, respectively. The three position switch 34 of the decade selector 28 also rotates a shaft l |2 to which is aixed the movable switch arms |15, H6, Il? and |I8 of a four gang tandem switch arrangel ment with each movable switch arm being engageable, `at the will of an operator, with its respective Check, Run or Zero contact.

Also as shown in Figs. 9 and l0, the button conftacts of the tandem switches controlled by knob 30 are numbered 1 to 0 and are thus ten in number, whereas the button contacts of the tandem switches controlled by knob 32 are eleven in number being marked 1 to 0 plus a button contact marked S. Thus each button contact corresponds to the indicia appearing on the front of the decade selector with which the pointer of knobs 30 and 32 register. In other words, button contact l of each tandem switch controlled by knob 39 corresponds to .010, button contact 2 to .020, etc., in steps of .010 each, with the tenth or zero button contact being an N. S. or no sample setting as hereinafter explained. In a similar manner, the button contacts controlled by knob 3'2 align with the indicia on the front of the decade selector with which the pointer of knob 32 registers and represent .011 for button contact 1, .012 for button Contact 2, etc., in steps of .001 up to .014, and buttons 5 to 9 representing .005 up to .009, with the zero button contact again representing N. S. or no sample and the eleventh button contact S being a sparef Likewise, the button contacts 55 and 51 of the two gang tandem switch controlled by knob 29 correspond to the indicia appearing on the front of the decade selector with which the pointer of knob 29 registers, with such graduations corresponding to .100, .200, etc.

As shown in Figs. 9 and 10, each button contact 16, of the rst tandem switch 59 of the deck controlled by knob 30, is connected by a conductor designated from .010 to .090 and N. S. to the movable contacts of a solenoid or relay H9 and from the xed contacts of this relay ||9 a conductor of the same designation (.010 to ..090 etc.) extends respectively to the plunger-contacts 56 carried by the respective insulated discs 41 and 50, which plunger-contacts 56 in Fig. l0 .have been designated by the same reference identification as the respective conductors connecting to them, for simplicity of understanding. Also, the No. 1 button contact 61 of switch 63 controlled by knob 29 is connected by a conductor .100 to a movable contact of relay ||9 and from a xed contact of the latter a conductor of the same designation extends to plunger-contact .100 of the respective insulating discs 41 and 50, thus placing the respective plunger-contacts 56 of insulating discs 41 and 50 under the control of relay I |9 for connection to tandem switch 59 and its button contacts 16. Likewise, the button contacts of the first tandem switch 84 controlled by knob 32 are individually connected by conductors designated .011; .012; .013; .014; .005; .006; .007; .008; .009; N. S. and S, to the movable contacts of a further solenoid or relay 20 and from the nxed contacts of this relay |20 a conductor of the same designation extends respectively to the plunger-contacts 56 of the respective insulating discs 46 and 49 bearing the same respective designation as the conductors connected to them, which thus places the discs 45 and 49 under control of relay |20 for connection to the tandem switch 84.

From Fig. 9 it will be noted that the button contacts 11 and 18 of the respective tandem switches 10 and 12 are connected in parallel to each other and with button contacts 15 of tandem switch 59. There is this distinction, however, to be noted which is that the tandem switch 10 adds one unit to each of the contacts of tandem switch 69 whereas tandem switch 12 subtracts one unit from tandem switch 09. For example, the .010 conductor which is connected to the No. 1 button of switch contacts 15 also connects in parallel with the No. 2 button of contacts 11 of switch 10 and with the No. 0 button of contacts 18 of switch 12. In a similar manner, conductor .020 connects with No. 2 button of switch contacts 16, with No. 3 button of switch contacts 11 and also with No. 1 button of switch contacts Thus, throughout the range of button contacts 16 of switch 09, the respective contacts 11 of tandem switch 10 which are connected in parallel with the button contacts 16 are one unit higher in the range from 1 to 10, whereas the button contacts 18 of tandem switch 12 are one unit less in the range from 1 to 10 from the respective button contacts 16 oi switch E9, with which they are in parallel. There is also one further distinction to be noted which is that the .100 conductor connected to No. 1 button of button contact 61 of switch 63 also connects to the No. 9 button of button contacts 18 of switch 12, and does not connect to any button contacts of the tandem switches 69 or 10.

In a somewhat similar manner the button contacts 96 of tandem switch 84, the button contacts 91 of tandem switch 55, and the button contacts 98 of tandem switch 85 are in electrical parallel with each other. Again, however, there is the same distinction to be noted which is that the button contacts 91 which are in parallel with button contacts 06 are respectively one unit less than that of button contacts 55, and button contacts 98 which are in electrical parallel with button contacts 96 are three units, respectively, below the latter. This may be readily appreciated by taking, for example, just one conductor which, as shown in Fig. 9, is connected to button No. 5 of button contacts 55 for switch 34, also to button No. 4 of button contacts 01 for switch 85, and which is also connected to button No. 2 of button contacts 0% for switch 85.

Regarding button contacts 19 of tandem switch 13, the majority thereof are not used, but buttons Nos. 1 and 2 are bridged together and connected by a conductor |22 to switch arm 84 of tandem switch 62, which conductor |22 also connects to a bridge of buttons Nos. 5 to 9, 0 and S, inclusive, of button contacts |03 of tandem switch 90, while the movable arm of tandem switch 13 is Vconnected by a conductor |23 to bridged buttons Nos. 1 to 4, inclusive of button contacts |83 of tandem switch 90. Buttons Nos. l to 9, inclusive, of button contacts 80 of tandem switch 14 are bridged together and connected by a conductor |25 to a bridge of buttons Nos. l to 9, inclusive, of button contacts 82 of tandem switch 15; with this same conductor |25 connecting with a bridge of buttons 5 to 9, 0 and S of button contacts 99 of tandem switch 81, to the movable arm of tandem switch 69, and also to the No. button of button contacts 81 of tandem switch 83. The No. 0 button of button contacts 80 of tandem switch 14 is connected by a conductor |26 of the movable arm 65 of tandem switch 83 While the movable arm of tandem switch 14 is connected by a conductor |21 to the No. 0 button of button contacts 82 of tandem switch 15 which conductor |21 also connects to a bridge of buttons Nos. 2 to 6, 8 and 9, inclusive, of button contacts |00 of tandem switch 88. Movable arm of tandem switch 15 is connected by a conductor |28 to a bridge of buttons Nos. 4 to 8, inclusive, of button contacts |82 of switch 89.

Referring now to tandem switch 81, its bridge of buttons Nos. l to 4, inclusive, of button contacts 99 are connected by a conductor |29 to the movable arm of tandem switch 19 and also to bridged buttons Nos. 1, S, 0 of button contacts |99 of switch 88, as well as to bridged buttons Nos. 0, S and l to 3,' inclusive, of button contacts |82 of tandem switch 89. The movable arm of tandem switch 81 is connected by a conductor |89 to the winding |44 of motor MI, (through terminal b of Fig. 9 to terminal b Fig. l0), as well as this conductor |38 being connected to the Zero contact of tandem switch H8. The next tandem switch 88 in the bank has its No. 7 button of button contacts |89 connected by a conductor |32 to the movable arm of tandem switch "i2 with such conductor also connected to the No. 9 button of button contacts |82 of tandem switch 85, while the movable arm of tandem switch 88 is connected by a conductor |33 to Contact H8 oi the tandem switch |95 controlled by switch lever arm 33. Movable arm of tandem switch 89 is connected by a conductor |38 to contact |98 of switch |88, while movable arm of tandem switch 98 is connected by a conductor |35 to both the Check and Zero contacts of tandem switch II which is operable by switch lever 3d, with such conductor |35 also extending (terminal f' Fig. 9 to terminal f Fig. l0) to one end of the winding of solenoid 21 (Fig. 10).

Movable arms of tandem switches |85 and |88 are connected to the respective Check contacts of tandem switches and IIS by the respective conductors |38 and |31 while contact |91 of switch |95 is connected by a conductor |38 to the movable arm of tandem switch 85 and likewise contact |99 of tandem switch |85 is connected by a conductor |39 to the movable arm of tandem switch 88.

Movable arm of tandem switch 84 is connected by a conductor |49 (through terminal a Fig. 9 to d Fig. l0), to one end of the shading eld Winding |82 of motor M2 (Fig. l0) with this conductor |68 also being connected to the Zero contact of tandem switch H5.

Considering now the four tandem switches controlled by knob 34, the Run contact of tandem switch ||5 is connected by a conductor |45 (terminal c Fig. 9 to c Fig. 10) to a junction |48 where it is connected to the N. S. conductor extending to the insulating disc 46 or 49, as well as to the buttons 0, 9 and 'I on the tandem switches 84, 85, and 86, respectively through the contacts of relay |20. The movable arm of this tandem switch ||5 is connected by a conductor |41 (terminal d Fig. 9 to d Fig. l0) to one end of the shading eld winding |018 of motor M4 (Fig. l0).

Likewise the Run contact of tandem switch l |I5 is connected by a conductor |49 (terminal e Fig. 9 to e Fig. 10) to a junction |59 where it connects to the N. S. conductor extending from the insulating disc 41 or 58 as well as from the buttons Nos. 0 and 1 of tandem switches |39 and 18, respectively through the contacts of relay ||9. The movable arm of this tandem switch IIS is connected by a conductor |52 (through terminal h Fig. 9 to h Fig. 10) to one end of the shading eld winding |53 of motor M3 (Fig. l0). Thel movable armA of tandem switch |I1 is connected by a conductor |54 (through terminal g Fig. 9 to g Fig. 10) to one end of the winding of solenoid 25. In a similar manner the Check and Zero contacts of tandem switch IIS are bridged (the Run contact being blank) and connected by a conductor |5I to one end of the winding of the respective relays ||9 and |28.

Referring now more specically to Fig. 10, it will be noted that the main iield windings FI, F2, F3 and Fd of the respective motors MI, M2, M3 and M4 are continuously energized from the source of supply LI, L2 of the customary commercial potential so long as the main line switch |55 remains closed. Also, the remaining end of the winding of the respective solenoids 25 and 21 are also connected to one side of the supply source L2, while the other side of the supply source LI is connected (through terminal z' Fig. l0 to i Fig. 9) to the movable arm of tandem switch I I8 and tothe No. l button of button contacts 56 of tandem switch 52 controlled by knob 29. As shown clearly in Fig. 10, the center point of each of the shading eld windings of the motors MI, M2, M3 and M4 is connected to ground at G and the remaining end of each of these shading eld windings is connected by conductors |58, |51, |58 and |59 through a xed resistor |82, |83, |813 and |85, respectively, to the plunger-contact 51 carried by the insulating discs 46, 41, 49 and 58, respectively. These motors MI to M4, inclusive, are of a somewhat unorthodox type in that,.although their main field winding is continuously energized, the rotor will not rotate until a portion of the shading eld winding is short-circuited, with direction of rotation being determined by the particular portion of the shading eld winding actually shortcircuited. Also, as previously mentioned, the ground G for the motors MI, and M2 is independent of the ground G for the motors M3 and M4, due to the fact the respective mechanisms are insulated from each other.

The present invention may be better understood by a description of a specic operation. Assuming, therefore, that the thickness of the material I9 which at the moment it is desired to roll on the mill 2i) is to be of .046 in thickness. Accordingly, the operator first sets his standard gauge for this thickness. To do this the operator rotates knob 29 to make its pointer align with the 0 graduation on the front of the decade selector 28 Ywhich also moves the arm 84 of tandem switch 82 so as to engage the No. 0 button of button contacts 88 and at the same time rotates arm 85 of tandem switch 63 so that it likewise engages the No. 0 button of button contacts 61. Next knob 30 ofthe decade selector 28 is rotated until its pointer registers Iwith the No. 4 graduation on the front panel ci the decade selector. Since rotation of knob 30 also rotates shaft 58, the movable arms of the tandem switches 63, 10, 12, 13, 14, and 15 will also be rotated into contact with the No. 4 button of their respective contact buttons 15, 11, 18, 19, 80 and 82; as shown in Fig. 9. Likewise knob 32 is rotated until its pointer registers with the No. 6 graduation on the front panel of the decade selector 28 and since this also rotates shaft 83, the movable arms of the tandem switches 84, 85, 85, S1, 88, 89 and 95 are rotated until they contact the No. 6 button of the respective button contacts 96, 91, 98, 99, 93, |32, and |03, also as shown in Fig. 9. At this particular moment the position of the switch lever arm 33 which rotates the arms of tandem switches |55 and |06 is immaterial, but switch lever arm 34 is moved `to its R or Run7 position, which simultaneously moves the of tandem switches H5, H6, ||1 and ||8 into engagement with their respective Run contact.

The main line switch |55 (Fig. l0) being closed will energize the main ileld windings FI, F2, and F4 of the motors Ml to M4, inclusive, as well as one side of the line (L2) being supplied to one end of the winding of solenoids 25 and 21 and to one end of winding of relays ||9 and |23. The various tandem switches being now in their ren spective positions as just described and as shown on Fig. 9, a circuit is completed to the forward or left hand portion of the shading neld winding |42 of motor M2 as shown in Fig. l0. This circuit is shown in a heavy line and extends from one end of such winding |42, through conductor |46 (also terminal a Fig. 10 to ci Fig. 9) rotatable arm of tandem switch 84, conductor to movu able contact of relay |26 (now deenergized and engaging its lower nxed .O06 contact) thence through the .006 conductor to the No. .006 plunger-contact 56 of insulating disc 45 (Fig. 10) and. since this plunger contact 56 engages the metallic disc 22 which is grounded -through its shaft 38 or brush contact 58, the circuit is completed to the left or F half (as viewed from Fig. l) of thez shading neld winding |42 thro-ugh the ground connection G of its center tap.

At the same time, current of a reduced value will also flow through the right or R half (again viewed from Fig. 10) of the shading field winding |42 from the end thereof through conductor |56 and resistor |62 to plungerecontact 51 carried by insulating disc 46 which, being in engagement, with the grounded metallic disc 22, completes the circuit to the center tap of the shading field winding |42. The purpose of the resistor |62 is to prevent the magnetic flux ci the R portion of the winding 42 from overcoming the magnetic flux trom the forward or F portion of such winding but the resistor |62 is of such value that satis. factory reverse torque of the motor M2 is obtained as hereinafter explained. Accordingly, the motor M2 will rotate in the forwarddirection, such as shown by the arrow in the schematic showing of Fig. 6, with the closed circuit as above traced indicated by the heavy lines. Rotation of motor M2 rotates shaft 38 and the metallic disc 22 until the No. .006 plunger-contact 55, radially aligned with the metallic insert of .O96 thickness rides over the larger area rectangular insum lating block 54 carried by the metallic disc 22. This interrupts the circuit to the forward or F portion of the Winding |42 thus stopping rotation of the, disc 22 with the .006 thickness insert prop- 10 erly aligned with the X-ray beam which emanates from the standard X-ray tube source 5.

There is, however, the possibility that the disc 22, together with the motor M2 and the gear train 31, will coast slightly thereby misaligning the desired metallic insert with the X-ray beam as shown in Fig. 7. To compensate for any such coasting or vibratory movement, and thus assure proper alignment of the metallic insert 55 with the X-ray beam, the larger area rectangular insulating block 54 permits the contact 56 to travel beyond perfect alignment without again closing the circuit to the forward or F portion of winding |42. However, any such coasting or vibratory movement will cause the plunger contact 51 to again engage the metallic disc 22, thus completing the circuit as previously traced, to the reverse or R portion of shading iield winding |42, as shown by the heavy line in Fig. 7, causing areverse rotation of motor M2 and disc 22 until the plunger-contact 51 rides on the smaller area insulating block 53 at which time the circuit to both portions of the motor winding |42 will be interrupted, with attendant complete alignment of the insert or opening 55 with the X-ray beam from the source 5, as shown in Fig. 5.

Simultaneously, with rotation of disc 22 in the manner above described, the metallic disc 23 also is rotated by its motor MI to align the .040 metallic insert with the X-ray beam from the source 5. The circuit to 'the motor MI, and as shown in heavy line, extends from one end of winding |44 through conductor |39 (to terminal b Fig. 10 to terminal b Fig. 9), to movable arm of tandem switch 81 which is in engagement with the bridge of buttons Nos. 5 to 9, 0 and S, or button-contacts 99, thence by means of conductor |25 to the movable arm of tandem switch 69 which is now in engagement with its No. 4 button of button-contacts 16, through conductor .04() to the movable contact of relay ||9 (now deenergized and engaging its lower xed .040 contact) and thence through the .040 conductor to the .040 contact of plunger-contacts 56 carried by insulating disc 41, and since such plunger contact engages the metallic disc 23 the circuit is completed through shaft 36 or brush 59 to ground and from ground G to the center tap of shading field winding |44. The motor MI accordingly rotates until the .040 plunger-contact 56 rides over the larger area insulating block 54 carried by the metallic disc 23 thus interrupting the circuit to motor Ml. Again should there be any coasting or vibratory movement tending to misalign the .040 metallic insert 55 with the X-ray beam from source 5, the plunger-contact 51 will complete the circuit to the reverse or R portion of motor winding |44, thus reversing rotation until such circuit is interrupted by plunger-contact 51 riding on the smaller area insulating block 53 radially aligned with the .O40 insert 55 and correctly aligning the insert with the beam, in the identical manner as previously described relative to metallic disc 22 and as shown in Figs. 5, 6 and 7.

The operator having now set the discs 22 and 23 so as to impose metallic inserts 55 having a total thickness of .046 in alignment with the X- ray beam from the standard source 5, it will be noted that with the tandem switches controlled by the knob 34 in the Run position a circuit is likewise simultaneously completed to the motor M3 and M4 So as to align the no sample or N. S. opening in the metallic discs |1 and I8 in alignment with the X-ray beam from the X-ray source 6. For example, a circuit to the motor M4 is completed from one end of the shading field winding |48 through conductor |41 (terminal d Fig. 10 to terminal d Fig. 9) to the movable arm or tandem switch now in engagement with the Run contact thence through conductor |45 (terminal c Fig. 9 to terminal c Fig. to the junction |46 which connects with the N. S. conductor extending to the plunger contact N. S. carried by the insulating disc 49 which, being in engagement with the metallic disc |1 in turn grounded by the shaft 43 or brush 58, completes the circuit to the motor from the ground G to the center tap of the motor winding |48, as shown by the heavy lines. Accordingly, the motor M4 rotates shaft 43 together with the metallic disc |1 until the N. S. plunger contact rides over the large area insulating block 54 to interrupt the motor circuit, thus aligning the N. S. opening 55 with the X-ray beam from the test source 6. If, however, there is any coasting or vibratory motion tending to carry the insert or N. S. opening 55 out of alignment with the X-ray beam, the reverse or R portion of the winding |48 is energized to cause reversal of the motor in the precise manner as previously described regarding the reverse operation of motors Ml and M2. Moreover, it will be noted that when motor M4 is energized, there is no feed back which affects motor M2 because the N. S. conductor extending from the junction |46 to the upper N. S. fixed contact of relay |28 is now open, since the movable N. S. contact of this relay at the moment is engaging the lower N. S. xed contact connected to disc 46.

Iny a similar manner a circuit is closed to the shading field winding |53 of motor M3 which extends from one end of the winding through conductor |52 (terminal h Fig. 10 to terminal h Fig. 9) to the movable arm of tandem switch H6 now in engagement with its Run contact and thence by conductor |49 (terminal e Fig. 9 to terminal e Fig. l0) to a junction |58 connected to the no sample or N. S. plunger contact of insulating disc 50 which plunger-contact engages the metallic disc I8. and thence to ground through shaft 40 or brush 59 and from ground G to the center tap of eld winding |53, as shown in heavy lines.

The motor M3 will thus rotate the metallic disc |8 until the contact-plunger N. S. rides over the large area insulating block 54 to interrupt the forward or F portion of the eld winding |53 which thus aligns the N. S'. opening with the X-ray beam from the test source 6 in the precise manner as previously described, with any coasting or vibratory movement tending to cause misalignment being corrected by reversal of the motor M3, in the same manner as above mentioned with respect to the other motors. It will again be noted that when motor M3 is energized, there is no feed back which alects motor MI, because the N. S. contact extending from the junction |56 to the upper N. S. xed contact of relay |I9 is now open, since the movable N. S. contact of this relay at the moment is engaging the lower N. S. xed contact connected to disc 41.

Having now set the gauge for a standard thickness of .046, the next operation is for the operator to check for the null point accuracy of the reading instrument. Accordingly, the switch lever arm 34 is then moved to the Z position, as shown on the front of the decade selector, which moves the tandem switch arms H5, ||6, ||1 and ||8 into engagement with their respective Zero 12 contacts. The movement of switch arm ||8 will cause energization of the winding of relays H6 and |20 with raising of their respective movable contacts into engagement with their upper xed contacts bearing the same designation. The respective motors MI and M2 will remain stationary as the previously traced circuits thereto are now interrupted by the movement of the contacts of the relays ||9 and |20. However, new circuits are now completed to the shading eld windings of motors M3 and M4 for the purpose of rog tating the respective metallic discs i1 and i6 to align the metallic inserts 55 now carried thereby which have the identical thickness, namely, .040 and .006, in alignment with the X-ray beam from the test source 6. The circuit to the motor M4 may now be traced from one end of the shading eld winding |48 through conductor |41 (terminal d Fig. l0 to terminal d Fig. 9) to the movable arm of tandem switch H5 now in enu gagement with its Zero contact, thence by means of conductor |48 to the movable arm of tandem switch 84 now engaging the No. 6 button of button-contacts 96, through conductor .006 to the movable .O06 contact of relay |26 now engaging its upper xed .006 contact and thence through the .006 conductor to the .005 plunger contact 56 carried by insulating disc 49 which is now in engagement with the metallic disc |1 and thus to ground through shaft 43 or brush 58 and from ground G to the center tap of eld winding |48. Inasmuch as the N. S. opening 55 in disc |1 was previously aligned with the X-ray beam from test source 3, the metallic disc |l will now rotate in a forward direction, such as shown by the arrow in Fig. 6, and when the .006 plunger contact 56 rides over the large area insulating block 54, the previously traced circuit to the motor winding |48 will thus be interrupted aligning the .006 insert 55 with the X-ray beam from the test source 6 which corresponds pre cisely to the .006 insert carried by the metallic disc 22 now in alignment with the X-ray beam from the Standard source 5.

Simultaneously, the circuit to shading field winding |53 of motor M3 is likewise completed which circuit extends from one end of the winding |53 through conductor |52 (terminal 71, Fig. 10 to terminal h Fig. 9) to the movable arm of tandem switch ||6 now engaging its Zero contact, thence by means of conductor |30 to the movable arm of tandem switch 81 now engaging the No. 6 button of bridged buttons 5 to 9, 0, S, inclusive, of button-contacts 99, through conductor |25 to the movable arm of tandem switch 69 now engaging its No. 4 button of button-contacts 16, through conductor .040 to the movable .040 contact of relay H9 now engaging its upper fixed .040 contact and thence through the .040 conductor to the .040 plunger-contact 56 carried by insulating disc 58 and engaging the metallic disc |8, the latter of which is grounded through its shaft 4D or brush 49 and thence from ground G to the center tap of shading eld winding |53.

Motor M3 is accordingly rotated in a forward direction, again as shown by the arrow in Fig 6, until the .040 plunger-contact 56 rides over the large area insulating block 54 to interrupt the circuit to the motor winding |53, at which time the .040 insert 55 carried by the metallic disc |8, will be in alignment with the X-ray beam from the test source 6 as well as with the .006 insert 55 carried by the disc |1.

Accordingly, inserts having a total thickness of .046 will now be interposed in the path of the X-L ray beam from the standard sourceA 5 and inserts having a similar thickness will be interposed in the X-ray beam from the test source 6. Inasmuch as both X-raybeams after passing through the respective inserts operate the pick-up which is amplied as previously described, the null meter should now indicate precisely zero, showing that the entire thickness gauge is properly set and functioning due to a complete balance of the test inserts carried by discs and I8, with the standard insertsA of like thickness carried by the standard discs 22 and 23.

In order now to still further check the accuracy of the thickness gauge setting, the'` operator moves the switch lever arm 34 to the c position on the decade selector 28 which accordingly moves the arms of tandem switches H5, H6, H1 and HB into engagement with their respective Check contacts. rlhe respective motors MI and M2 will still remain stationary since the circuit thereto is again broken bythe relays I9 and |20, as movement of arm H8 to its Check position immediately reenergizes the winding of the relays I |9 and |252 and at the same time the previously traced circuit to the windings |53 and |58 of the motors M3 and M4, respectively, are likewise interrupted by these relays I IS and |20. lt will be recalled that at the instant of movement of the switch lever arm 34 to the Check position, the metallic discs I8, 23 had their .040 insert in alignment with the X-ray beam from the respective sources and 6 and likewise the .0.06 inserts carried by the discs 22 had their .006 insert in alignment with the X-ray beam from the respective sources 5 and 6.

Consequently, the discs 22 and 23 carrying the standard inserts remain undisturbed since the circuit to the respective motors Ml and M2 remains interrupted by the relays H9 and |20 as above noted. However, upon movement of the arm of tandem switch H5 to its Check contact a circuit to the winding |48 of motor M4 is now completed through a circuit which extends from one end of the winding |48 through conductor |41 (terminal d Fig. l0 to terminal d Fig. 9) the movable arm of switch H5 now in engagement with its Check contacts, thence by means of a conductor |36 to the movable arm of tandem switch |05 shown in engagement with its contact terminal |59, through conductor |39 to the movable arm of tandem switch 86 now engaging the No. 6 button of its button contacts 88 through the .009 conductor to the movable .009 contact of relay now engaging its upper fixed .009 contact and thence by the .069 conductor to the .O09 plunger-contact 56 carried byl insulating disc 49 and now engaging the metallic disc |f'|, thence to ground through shaft 43 or brush 58 and from ground G to the center tap of winding |48. Again the forward or F portion of winding |48 is energized, which causes rotation of metallic disc I1 until the .009 metallic insert 55 aligns with the X-ray beam from test source E.

However, disc |8` which still has its .040 metallic insert 55 in alignment with the X-ray beam from the test source 5 remains stationary, since its driving motor M3 is not energized due to interruption of the circuit to the field winding |53 by the .04D plunger contact 56 of the disc 5U resting on the large area insulating block 54 carried by disc I8. While the circuit to the winding |53 remains interrupted by such plunger contact, a change is nevertheless made in the circuit previously extending to such winding. Such change results from the fact that when the movable arm H5 engages its Check contact, a by-pass circuit is completed to a portion of the previously described circuit, extending to the movable arm of tandem switch 69. Such by-pass circuit extends from the Check contact terminal of tandem switch H53 through conductor |37 to the movable arm oi tandem switch |66 now engaging its terminal thence by conductor |33 to the movable arm of tandem switch SB now engaging its No. 6 button of button-contacts |93, thence by conductor iii? to the movable arm of tandem switch l now engaging its No` 4 button of button contacts et and thence means of conductor |25 to the movable arm of tandem switch 5S forming part of the .040

circuit to the motor M3 as previously traced.

Owing to the fact that, under the conditions previcusly described the switch lever arm was in registration with its .003l graduation on the decade selector 28, which thus placed the tandem switch arms |95 and in engagement with their respective contacts it@ and iiii, this caused rotation of the metallic disc il, from its previous position with the .006 metallic insert in alignment with the X-ray beam from test source 6, to position its .009 metallic insert 55 in alignment with the X-ray beam The thickness reading instrument, or null rneter, should now indicate that the thickness of the metal interposed in the X-ray beam from the test source 5 is .003 above standard, since the total thickness of the metal interposed in the i-ray beam from the Standard source 5 totaled only .646. In order to still further check the indication of the thickness reading instrument or null meter, the

Yoperator now moves the switch lever arm 33 to cause it to register with the .001 graduation on the decade selector' 28.

Such movement rotates the shaft |234 causing the movable arms of tandem switches H35 and 1:36 to leave their respective contacts it and i?! and to engage their contacts It? and ist. This movement accordingly again completes a circuit to the shading i-leld winding Hi8 of the motor M4 which extends from one end of the winding |48 through conductor is? (terminal d Fig. 1U to d Fig. 9) to the movable arm of tandem switch H5 still engaging its check contact, thence through conductor |35 to the movable arm of tandem switch It now engaging its .Gl contact |91, through conductor I 38 tc the movable arm of tandem switch which is engaging its No. o button of button-contacts Si and then through the .007 conductor to the movable .007 contact, now still engaging its upper fixed .|337 contact, and. thence through the .007 conductor to the No. .007 plunger-contact 5: on insulating disc il which being in engagement with the metallic disc ll connects again to ground through motor shaft 43 or brush 5S and from ground G back to the center tap of shading ield winding The motor accordingly rotates metallic disc l1 until its .007 metallic insert 55 aligns with the X-ray beam from "test source E and with the .040 metallic insert 55 carried by metallic disc I8 which has again remained stationary despite a slight change in circuit connects. For example, the circuit from the winding |53 up to the movable arm of the tandem switch Ist remains the same. However, the latter now engages its .001 contact IDS thus interrupting the previously traced part of the circuit including the tandem switches 88 and l 4 but now completing a by-pass circuit extending from the contact |63 through conductor |34 to the movable arm of tandem switch 89 engaging its No. 6 button of bridged button-contacts |02, thence through conductor |28 to the movable arm of tandem switch 'I5 engaging its No. 4 button of bridged buttoncontacts 82 and thence through common conductor |25 to the movable arm of tandem switch 69 included in the previously traced circuit which is interrupted by the .040 plunger-contact 5B carried by insulating disc resting on the insulating block 5d.

Movement of the switch lever 33 to its .001 position thus caused the .007 metallic insert 55 carried by metallic disc Il. to move into alignment with the beam from test source 6 and the .040 insert 55 carried by metallic disc I8, now making a total thickness of .047, compared with the .046 thickness interposed by the inserts carried by discs '22 and 23 in the X-ray beam from the Standard source 5. The null meter will accordingly record a deection from its Zero graduation to a .001 graduation instead of the .003 graduation as recorded when the switch lever 33 was in its .003 position. 1t will be noted that when the operator makes his .001 or .003`

check, an insert of either of these thicknesses is not added to the total thickness of the balance or Zero check but instead a metallic insert of either the .001 or .003 greater than the particular thousandths (.000) insert in the path of the standard X-ray beam is moved into position to intercept the test X-ray beam. Moreover, by stepping the connections, as previously mentioned, between the button-contacts of the respective tandem switches 59, I0 and 12, whereby tandem switch 'l0 adds one unit to that of tandem switch 39 while tandem switch 'l2 subtracts one unit from switch 99, this causes movement of the disc Ill with its thousandths (.000) inserts, while maintaining the circuit to the motor for disc I8 carrying the hundredths (.00) inserts interrupted, despite a slight change in a part 0i' such motor circuit by operation of the switch lever 33 and its tandem switches |55 and I 05. Also, since the circuit to the motors MI and M2 was interrupted by the relays I|9 and |20, there has been no change in the .0116 standard setting of the discs 22 and 23.

Having now made a balance or Zero check and both a .001 and .003 check and the entire thickness gauge having been found to be accurate, it is now ready for operation to measure the material I 9 of .046 thickness as it comes from the rolling mill 20. The operator now accordingly moves the switch arm 34 back to its Run position, which again partially closes the previously traced circuits to the shading field winding of the motors MI and M2, since relays H9 and |20 are deenergized upon movement of tandem switch IIS to its Run position, but since the circuits to the windings |42 and |44 are still interrupted, due to their respective .040 and .006 plunger contacts 56 resting on their insulating block 54, the motors are not energized, with the result that the standard discs 22 and 23 remain in position interposing metallic inserts 55 having a total thickness of 0.46 in position to intercept the X-ray beam from the standard source 5. However, upon movement of the switch lever 34 as just mentioned, the tandem switches H5, Il@ and Hl are likewise again returned to their Run position which immediately completes a circuit to the shading field windings |48 and |53 of the respective motors M4 and M3, as previously traced. Thus, regardless of the momentary setting of the test discs and I 9, they will be rotated until their respective N. S. or no sample opening aligns with the X-ray beam from the test source B. The rolling mill 20 is then started and the only thickness thereafter interposed in the path of the X-ray beam from the test source 6 is that of the material I9, the N. S. positions of the discs I'I and I8 being merely openings without inserts. So long as such material remains at the thickness of the .046 set as "standard by the discs 22 and '23, the null meter will read 0 but upon any variation from such thickness by the mateu rial I9 it will be indicated in thousandths by the meter deflection.

The foregoing example assumed a thickness of .046 for the standard setting and that desired for the material I9 as it came from the rolling mill 20. Should a thickness of say .146 be desired, the operator need only rotate the knob 29 until its pointer registers with the .1 graduation on the selector panel 28. Since such rotation of knob 29 also rotates, the shaft 62 tandem switch arm 64 is moved away from its previous 0 buttonv into engagement with the No. 1 button of button contacts 66 and in a similar manner tandem switch 65 also leaves its 0 button and engages its No. 1 button of button contacts 61. So far as tandem switch 65 is concerned at this time, it merely connects the 0 button of button contacts of tandem switch 14 through conductor |26 to the No. .100 conductor, instead of to the conductor |25 as was previously the case. However, the engagement of tandem switch 64 with its No. 1 button closes a circuit to the winding of the solenoid 21 which extends from one side of the supply source LI (terminal i Fig. 10 to terminal i Fig. 9) to the No. 1 button of button contacts 66, through tandem switch armvd and conductor |22 to the bridged button contacts I [I3 of tandem switch 90, thence through conductor' |35 (terminal f Fig. 9 to terminal f Fig. l0) to rone end of the winding of solenoid 2l and sinceV its other end is connected to the other side of the supply source L2, the solenoid 2'I is accordingly energized. Upon such energization the solenoidretracts its armature against the tension of a coil spring thus moving the flag-gauge 23 into position to be intercepted by the X-ray beam from the standard source 5 where it remains so long as a thickness of .100 to .199 is desired. Of course the thickness of the flag-gauge 26 may be altered as occasion necessitates by substituting a gauge of .200 or .300 for the .100 gauge in which event the knob 29 is rotated to align its pointer with the desired graduation on the selector panel 28.

In order to properly check the entire thickness gauge for thicknesses of .100 or .200, etc., a similar flag-gauge 24 is provided which is automatically positioned to be intercepted by the X-ray beam from the test source 6 when the switch lever 34 is moved to its Check or Zero positions. This is accomplished by movement of the tandem switch arm II'I. By reference more particularly, to Fig. 9, it will be noted that when in the Run position of switch lever 34 the Run contact of tandem switch II'I is effectively a blank contact, whereas the Zero and Check contacts are bridged together and also connected to the conductor |35. Since this latter conductor is a part of the circuit as above traced for energizing the winding of the solenoid 21, it follows that when the tandem switch arm .H1 engages either its Check or Zero con- 17 tacts the winding of the solenoid 25 is connected in parallel with the winding of the solenoid 21 This is due to the fact that the tandem switch arm ||1 is connected by conductor |54 (terminal g Fig. 9 to g Fig. l0) directly to one end of the Winding of solenoid 25. Accordingly, during the Check and Zero positions of the tandem Switch ||1 both solenoids 25 and 21 are energized thus positioning a flag-gauge 24 and 26, respectively, of identical thickness in the path of both the standard source 5 and the test source 6. However, upon return of the switch lever 34, together with the tandem switch ||1, to the Run position, the winding of solenoid 25 is deenergized while the solenoid 21 alone remains energized to maintain its flag-gauge 26 in the path of the beam from the standard source 5, so long as the knob 29 remains with its pointer in alignment with any graduation other than its graduation and upon movement of the pointer of knob 29 to this 0 graduation, the solenoid 2l' is then deenergized.

As previously pointed out, the metallic inserts 55 carried by the metallic discs I8 and 23 consecutively increase in steps of .010 While the metallic inserts 55 carried by the metallic discs l1 and 22 likewise increase in steps of .001 but not necessarily consecutively throughout their entire range since there is a gap between the insert 55 of .009 thickness and that of .011. This is because an insert 55 carried by the metallic discs I8 and 23 has a thickness of .010 so that when the latter thickness is desired only this insert is positioned by the .discs I8 and 23 in the path of the X-ray beams from the sources and 6 while the discs .1 and 22 will align their respective N. nS. or no sample, opening with the X-ray beams and the inserts o`f'-010`thickness. Also, for certain thicknesses, the inclusion of the respective pairs of inserts are automatically additive in a slightly different manner,u to" give the desired total merely by setting of the pointers of the knobs 30 and 32 to 'the-- properv desired graduation. Y

This may be better appreciated by taking asA an example a thickness setting of say .054. The ioperator will as previously mentioned rotate knob 30 until its pointer aligns with the No. 5 graduation and similarly the pointer of knob 32 is aligned with its No. 4 graduation. Such rotation of knob 30 accordingly rotates the tandem switches 60, 10, 12, 13, 14 and 15 into engagement with the No. 5 button of their respective button contacts and tandem switches 84, 85, 86, 81, 8,8, 89 and 90 are rotated by knob 32 until they engage the No. 4 button of their respective button contacts. Although the No. 5 button of button contacts 16 of tandem switch 69 is connected through the .050 contacts of relay I9 to the .050 conductor extending to plunger-contact 56 of insulating disc 46, this conductor is not placed in circuit because of the fact the previously traced circuit which included tandem switch 69 is open at tandem switch 81 since the latter now engages its No. 4 button of its button-contacts 99. Accordingly, for this assumed setting of .054 tandem switch 69 may be disregarded. Moreover, inasmuch as the previously traced circuit for the motors MI and M2 at the .046 thickness setting clearly indicated that the conductors |30 and |40, respectively, formed part of their energizing circuits, these conductors may be taken from Fig. 9 as the motors, for illustrative purposes.

At the assumed setting of .054, it will be noted that conductor |30, which connects to tandem 18 switch 81, now completes the circuit to the No. 4 button of its buttoncontacts 99 and that such No. 4 button is connected Aby conductor |29 lto the arm of tandem Switch 10. The latter, however, is now in engagement with its No. 5 button el button-contacts 11 but such No. 5 l1button connects with the .040 movable contact engaging the lower ixed .040 contact of relay H9 and to the .040 conductor extending to the insulating disc 41- since the button-contacts actually add one unit to the button-contacts 16 of tandem switch 59'.' By this differential, although the arm of tandem switch 10 is in engagement with its No. 5 button, since the button adds one unit, aspreviously mentioned, to tliebutton-contacts 16 of tandem switch 69,v such No. 5 button actuallyvs connected to the .040 conductor. vThis accordingly now completes a circuit, as previously traced, until the .040 insert carried by theV metallic-disc 23 is rotated into alignment with the VX-r'ay beam from the standard source 5 bythe motor Ml v`(unless it sho-nld happen that the .040 insert 55 of the disc 23 were alreadyi'n such position, in which event the disc 23 will remain stationary), despite the setting of the pointer of knob 30 at its No. 5 graduation..

At the same time the setting of the pointer lof knob 92 at its No. 4 graduation causes theV tandem switch 84 to be moved to its No. 4 button of the button-contacts 96 and since this No. 4 button is connected through the .014 movable Contact engaging the lower xed .014 contact of relay |20 to the .014 conductor, a circuit is completed from conductor |40 through tandem switch 84, conductor .014 and the .O14 contacts of relay |20 to the .014 plunger-contact 56 on insulating disc 45, until the motor M2 rotates the .014 in'- sert 55 carried by metallic disc 22 into alignment with the X-ray beam from the "standardt source 5. The automatic positioning of the .G40 and. the

.014 inserts 55 carried by the respective metallicV discs 23 and 22 in alignment with the iXi-ray beam from the standard source 5 thus makes a total thickness of .054 whichV is the setting se'- lected by the knobs 30 and V32 on the selector panel 28. By the same token, movement of the switch lever 34 to its Zero position will in no way disturb the circuit connections to the motors MI and M2 as the circuits thereto will be interrupted due to energization of relay |20 by movement o1" tandem switch |8 to its Zero position, resulting in the discs 22 and 23 remaining in their position interposing the total of .G54 thickness in the X-ray beam. .Such movement will now, however, complete energizing circuits to the motors M3 and M4 in the manner previously traced due to energization of the relays H9 and |20 by movement of tandem switch IIS, except that the .040 and .014 contacts of relays I9 and |20, together with the conductor .040 and .014

respectively, are now part ofthe energizing circuit for the motors M3 and M4. The .040 metallic insert 55 and the .014 metallic insert 55 carried by the respective discs I8 and |1 are accordingly rotated into alignment with the X-ray beam from the source 6, so that a balance or Zero check can be made in the same manner as previously described with respect to the originally assumed setting of .046. A

Having made such check with the null meter i being undeflected, the switch lever 34 may then be moved to its Check position. Again the circuits to all motors MI to M4 inclusive to the windings of'relays ||9 and |20, are interrupted- V by the tandem switches |I5, and H6, but additional lcircuits are now completed to themotors M3 and M4 by switches |I5 and ||6, as well as the. energizing circuit for the windings of relays |19 and |20 beingV again closed by the movement of tandem switch II8 to its check position. This accordingly causes these latter motors M3 and M4 to become energized with such circuits depending upon the setting of switchlever 33 for the,.003 or .001 setting. Taking rst the .003 setting of tandem switches |05 and |06 as shown in Fig. 9, the circuit for the motors M3 will now extend` from one end of shading field winding |53 through conductor |52 (terminal h Fig. 10 to h Fig. 9), tandem switch ||6, Check contact thereof and conductorV |31to tandem switch |06. contact ||0, conductor |33 to arm of tandem switch88 now engagingr its No. 4 button of its bridged button-contacts |00, conductor |21 to arm of tandem switch 14 now engaging its No. 5 button of bridged button-contacts 80, thence by conductor |25 to arm of tandem switch 69 now engaging its No. 5 button of button-contacts 16.

It will be recalled that this switch 69 was not previously in the circuit, but on the contrary a circuit was` made through tandem switch to the .040 conductor which thus previously energized motors MI and M3 to position their respective .040 insert 55 in the path of the X-ray beam from the sources 5 and 6. Moreover, since the circuit to the motor MI is interrupted at the moment by the contacts of relay ||9, the .040 insert carried by metallic disc 23 still remains in the path of theX-ray beam from the standard source 5. However, since the .050 conductor extending from the No. 5 button of button-contacts 16 of tandem switch 69 is now actively conducting current, a circuit is thus completed through the .050 contacts of relay l I9 (now engaging its upper .O50 fixed contact) and by conductor .050 to the .050 plunger-contact I56 on insulating disc 50, thence to the metallic disc I8 engagedby the plunger-contact 56 to ground through shaft 40 or brush 59 and from ground G to the center tap of shading field winding |53'. Motor M3 thus rotates and replaces the previous .040 insert 55 carried by disc I8 with its .050 insert in the path of the X-ray beam.

Simultaneously, a circuit is also completed to motor M4 upon rotation of switch lever 34 to the Check position. Thiscircuit extends from one end of Vthe shading field winding |48 through conductor |41 (terminal d Fig. l0 to d Fig. 9), tandem switch I I5 noW engaging its Check contact, through conductor |36 to tandem switch |05 engaging its .003 contact |99, through conductor |39 to the arm of tandem switch 83 now engaging its No. 4 button of button-contacts 98 and thence through the .007 contacts of relay |29 (now engaging its upper .007 xed contact) and by the .O01 conductor to the corresponding .007 plunger-contact 56 carried by insulating disc 49 which at this time is engaging the metallic disc I1, thence to ground through shaft 43 or brush 58 and lfrom ground G to the center tap of field winding |48. Motor M4 thus rotates to replace the previous .014 insert 55 carried by metallic disc I1 with its .007 insert 55 in the path of the X-ray beam from the test source 6. Since the cire cuit to motor M2 was interrupted by the contacts of relay |29, the standard setting of .054 made up by the .040 and .014 inserts carried by metallic discs 22 and 23 thus remains in the path of the X-ray beam from the standard source 5. However, discs I1 and I8 now interpose a .050 and a .007 insert in the path of the X-ray beam from 20 testsource 6 which makes a total of .003 greater' which should thus be recorded by deflection of' the thickness instrument or null meter to its .003 graduation.

Again as a further check test the switch lever 33 may be moved to its .001 position which still leaves the motors MI and M2 deenergized with the .040 and the .014 inserts 55 carried by the re'- spective discs 22 and 23 aligned with the X-ray beam from the standard source 5, since the circuit to such motors remains interrupted by the contacts of relays ||9 and |20. Also, the circuit to the motor M3 likewise remains deenergized' clespite a slight alteration in a part of the previously traced circuit, thus retaining the .050 metallic insert interposed in the path of the X-ray beam from the test source 6. For example, instead of the previously traced energizing circuit for the motor M3 being through the switches |96, 88, 14 to the switch 69, upon movement of tandem switch |66 to engage contact |88, a partial circuit will now extend by conductor |34 to arm of tandem switch 89 still engaging its No. 4 button of button contacts |02, through conductor |28 to the arm of tandem switch 15 still engaging its No. 5 button of button contacts 82, and through conductor |25 again to the arm of tandem switch 69 which formed part of the previously traced circuit. Since such circuit is open, due to the engagement of the .050 plunger-contact 56 carried by insulating disc 50 with the insulated block 54 on the metallic disc I8 the motor M3 remains stationary even though contacts of relay |I9 are closed at this moment.

Simultaneously, however, engagement of tandem switch |05 with its .001 contact |01 completes a new energizing circuit to the motor M4. This circuit now extends from one end of the winding |48 through conductor |41 (terminal d Fig. 10 to d Fig.V 9) to tandem switch arm I5 still engaging its Check contact, thence by conductor |36 to tandem switch arm |05 now engaging contact |01, through conductor |38 to arm of tandem switch still engaging the No. 4 button of button contacts 91, and, since such button is connected to the .005 conductor extending through the movable and upper xed .005 contacts of relay |20 to the .005 plunger-contact 56 carried by insulating disc 49 now engaging the metallic disc |1, the circuit is completed through the shaft 43 or brush 58 to ground and from ground G to the center tap of shading eld winding |48. The motor M4 accordingly rotates replacing the .007 metallic disc 55, with the .005 metallic disc 55 carried by metallic disc |1 in alignment with the X-ray beam from test source 6. Thus, the .050 insert of disc I8 and the ,005 insert of disc I1 will total'.055 which is .001 more than the total of the .040 and the .014 inserts of the respective discs 23 and 22, thus causing a .001 deflection of the null meter.

All checking tests having shown the entire thickness gauge to be properly functioning, the operator then moves the switch lever 34 to its Run position on the panel of the decade selector 28 as previously explained. Such movement again causes the motors MI and M2 to still remain deenergized because, even though their respective energizing circuits are again partially closed by the contacts of relays ||9 and |20, due to energization of their windings upon movement of tandem switch II8 to its Run position, such circuits are nevertheless still interrupted by the respective .040 and .014 plunger-contacts 56 being in engagement with the large rectangular insulatnig block 54 carried by the respective metallic discs 23 and 22. However, inthe same manner as previously explained, the movement of the switch lever 34 to the Run position automatically causes re-energizaton of the motors M3 and causing them to rotate the discs I1 and I8 and align their respective N. S.. or no sample opening 55 with the X-ray beam from the test source Ij, thus conditioning the thickness gauge for measuring the material I9 Vfor a thickness of .0,54v as it comes from the rolling mill 20.

Although only two specic illustrations have been described in detail for thickness settings of the X-ray thickness gauge of the present invention, it will be obvious that any desired setting of the knobs 29. 30 and 32 will align the proper thickness inserts 55 as well as the flag-gauge as desired, with the X-ray beam from the standard source 5, within the range of .005 to .199 inch, and the same is true for the inserts 5 interposed in the X-ray beam from the test"A source 6. Moreover, it follows from what has been shown and described that the tandem switch 84 is the actual selector for the thousandths group of samples from .005 to .014, while tandem switch 85 functions to enable switching to a test sample of .001 more than the set sample. In a similar manner tandem switch 88 functions to enable rotation of the test turret disc I1 to a metallic insert 55 having a thickness of .003 greater than the set sample carried by disc 22 at any moment and tandem switch 81 determines when an insert, .010 lower than the value of the hundredth digit on which the switches controlled by knob 30 are resting at a given moment, is automatically interposed in the beam from the test source 6. The tandem switches 88 and 89 obviously operate in conjunction with the tandem switches 86 and 81 to allow for stepping-.up when the decade selector is set so that the desired setting causes the switches to pass over from a .007 or a .009 metallic insert. The purpose of tandem switch 98 is to synchronize the thousandths selector, or knob 32, with the tenths and hundredths settings by control knobs 2U and. 30, when selection at any time passes through 100. mills.

As to tandem switches 89 and 18 controlled by knob 30, they operate in the same manner as above described with respect to the tandem switches 84 and 85, except that they select thicknesses in step of hundredths (.010). Likewise tandem switch 12 operates in conjunction with the step-up feature brought about by tandem switches 88 and 89, as above mentioned, and tandem switch 13 operates to enable a second group of sample inserts 55 to work in conjunction with the 0.1 sample insert as the setting is increased from .104 to .105. Tandem switch 14 on the other hand operates in conjunction with tandem switch 88 to synchronize the step-up feature, while tan-.- dem switch 15 also cooperates with tandem switches 88 and 89 in connection with this step-,up feature. Relays IIS` and |28 operate undencon.- trol of switch IIIl to select the circuits forthe motors MI and M2 at one setting and to select the circuits for motors M3 and M4 at their other setting of the relays I I9 and |28, thus eliminating any possible feed back through the grounded center point of the respective motor windings.

From the foregoing it should thus become obvions to those skilled in the art that an X-ray thickness gauge is herein shown and described which is automatically operable in response to. initiation by an operator from aremotely disposed control cancl- Bytheprcvison of. a turret havine e plurality of metallic. inserts of various known thicknesses, which are selectively movable into the path of an X-ray beam from a standard source, a standard gauge thickness is thus set for the entire gauge. Also by providing a second turret having identical thickness metallic inser-ts and which are selectively movable into the path vci' an X-ray beam from a test source, a balance test Aof the thickness gauge can thus be made to show that the gauge is operating accurately owing to a recorder or register, such as a. null meter or the like, showing no deflection and remaining fixed at its 0 graduation. As a still further` accuracy test the test turret is automatically operable in response to initiation by an operator to interpose metallic inserts having known preselected slightly greater thicknesses in the path of the X-ray beam from the testsource. which selected increase thicknesses are registered by the meter deflecting to a graduation corrQSPOnding precisely to the increase thickness of the inserts interposed in the path of the X-ray beam from the test source above the thicknesses of the inserts interposed at any moment in the path of the X-ray beam from the standard source. Moreover, after making such check tests for accuracy the test turret is then automatically operable to condition the thickness gauge for measuring material as it comes from the rolling mill of the thickness as selected and set at the moment by the standard turret.

Although one specic embodiment of the present invention has been shown and described, it is to be understood that other modifications tnereof may be made without departing from the spirit and scope of the appended claims.

I claim:

l. An X-ray thickness gauge for measuring material thickness comprising a standardsource of X-rays and a test source of X-rays, light sensitive means responsive to the intensity of the X-ray beam impinging thereon from said standard source and said test source and operable able means disposed adjacent the path of the X-ray. beam from said test source and pro-.- vided with a plurality of gauge members of various known thicknesses similar to said first-mentioned gauge members as well as having a nogauge index and movable into a position to intercept the X-ray beam from said test source, and selector means electricallyA connected to both said remotelyv operable means and operable by an operator to preselect the particular gauge members interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular gauge members at the same moment interposed in the path of the X-ray beam from said test source for the purpose of making a balance check that the thickness of the gauge` members intercepting both X-ray beams are of equal thickness, and said selector meansI being also operable to automatically cause said second mentioned remotely operable means to position its .no-gauge index in the path of they .Kr-ray i' beam from said test source during operation of said thickness gauge for measuring material of unknown thickness.

2. An X-ray thickness gauge for measuring material thickness comprising a standard source of Xerays and a test source of X-rays, light sensitive means responsive to the intensity of the X- ray beam impinging thereon from said standard source and said test source and operable tov cause a registration of the intensity of the X-rays from said sources as a measure of mate rial thicknesses when interposed in said X-ray beams, mechanism disposed adjacent the path of thevX-ray beam from said standard source and provided with a plurality of gauge members of various known thicknesses movable into a position to interceptthe X-ray beam from `said standard source, a second similar mechanism disposed adjacent the path of the X-ray beam from said test source and provided with a plurality of gauge members of. various known thicknesses similar to said iirst mentioned gauge` members as Well as having a no-gaugeindex and movable into a position to intercept the X-ray beam from said test source, a remotely disposed selector panel electrically connected to both said mechanisms and operable by an operator to preselect the particular gauge members interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular gauge members at the same moment interposed in the path of the X-ray beam from said test source for the purpose of making a balance check that the thickness ofthe gauge members intercepting both X-ray beams are oi equal thickness, and said selector panel being also operable to automatically cause said second mentioned mechanism to operate and position its nogauge index in the path of the X-ray beam-from said test source during operation of said thickness gauge for measuring material of unknown thickness. i i l 3. An X-ray- -thickness gauge for measuring material thickness comprising a standard source of X-rays and a test source of X-rays, light sensitive means responsive to the intensityof the X-ray beam impinging thereon from said standard source and said test source and operable to cause a registration of the intensity of the Y-rays from said sources as a measure of material thicknesses when interposed in said X-ray beams, remotely operable means disposed adjacent the path of the X-ray beamfrom said standard source and provided with a plurality of gauge members of various known thicknesses movable into a position to intercept the X-ray beam from said standard source, a second re-v motely operable means disposed adjacent the path of the X-ray beamirom said test source and provided with a plurality of gauge members of various known thicknesses similar to said first4 mentioned gauge members as well as having a nogauge index and movable into a position to intercept the X-ray beam from said test source, selector means operable by an operator to preselect the particular gauge members interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular' gauge members at the same moment interposed in the path of the X-ray beam from said test source, control means operable by said selector means and electrically connected to both said remotely operable means to cause automatic operation of the latter with attendant movement-oi the saugemembersoi said-rstf-mentioned remotely operable means and having-the desired thickness as selectedy by said selector means into position to intercepty the X-ray beam from said standard source and-to automatically vcause movement of the no-gauge index of said second-mentioned remotely operable means into interposed vposition with the X-ray beam from said test source, to condition said thickness gauge for measuring the thickness of unknown material interposed in the X-ray beam -from said test source by comparison withthe thickness of the gauge members at the moment interceptingV the X-ray beam from saidA l-standardsource; and said selector means being operable to cause said control means to automatically operate said'second mentioned remotely operable means and position the Ygauge members having the same total thickness as the gauge members at the same moment intercepting the iX-ray beam from said standard source, in the path of the X-ray beam from said -test.source for `making a balance check of said thickness gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of the equal thicknesses of said gauge members.

4. An X-ray thickness gauge for measuring material thickness comprising a standard source ofX-rays and a test source of X-rays,

light sensitive means responsive to the intensity of the X-ray beam impinging thereon from said standard source and said test source and operable to cause a registration of the intensity of 4the 'X-rays from said sources as a measure of material thicknesses when interposed in said X-ray beams, mechanism disposed adjacent the path. of the X-ray beamirom said standard source and provided with a plurality of gauge members ofY various known thicknesses movable into a position to intercept the X-ray beam fromy said standard source, a second similar mecha.

nism. disposed adjacent the path of the X-ray beam from said test source and provided with a Aplurality of gauge members of various known thicknesses similar to said first-mentioned gauge members as well as having a no-gauge index and movable into a position to intercept the X-ray beam from .said test source, a remotely disposed selector panel operable by an operator to preselect the particular gauge members interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the. particular gauge members at the same moment interposed in the ,path of the X-ray beamirom said test source, control means operable by said selector means and electrically connected to both said mechanisms to cause automatic operation of the latter with attendant movement of said gauge members of said rst mentioned remotely operable means and having the desired thickness as selected by said selector means into position to intercept the X-ray beam from said standard source and to automatically cause movement of the no-gauge index of said second mentioned remotely operable means into interposed position with the X-ray beam from said test source, to condition said thickness gauge for measuring the thickness of unknown material interposed in the X-ray beam from said test source by comparison with the thickness of the gauge members at the moment intercepting the X-ray beam from said standard source; and said selector means being operable to cause said control means to automatically .operate said second mentioned.l`

remotely operable means and position the gauge members having the same total thickness as the gauge members at the same moment intercepting the X-ray beam from said standard source, in the path of the X-ray beam from said test source for making a balance check of said thickness gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of the equal thicknesses of said gauge members.

5. An X-ray thickness gauge for measuring material thickness comprising a standard source of X-rays and a test source of X-rays, light sensitive means responsive to the intensity of the X-ray beam impinging thereon from said standard source and said test source and operable to cause a registration of the intensi-ty of the X-rays from said sources as a measure of material thicknesses when interposed in said X-ray beams, remotely operable means disposed adjacent the path of the X-ray beam from said "standard source and provided wi-th a plurality of gauge members of various known thicknesses movable into a position to intercept the X-ray beam from said standard source, a second remotely operable means disposed adjacent the path of the X-ray beam from said "test source and provided with a plurality of gauge members of various known thicknesses -similar to said firstmentioned gauge members as well as having a nogauge index and movable into a position to intercept the X-ray beam from said test source, selector means operable by an operator to preselect the particular gauge members interposed at a given moment in the path of the X-ray beam from said standard source and lto preselect the particular gauge members at the same moment interposed in the path of the X-ray beam from said test source, control means operable by said selector means to cause automatic operation of both said remotely operable means and attendant movement of the gauge members of said rst-mentioned remotely operable means land having the desired thickness as selected by said selector means into position to intercept the X-ray beam from said standard source and to automatically cause movement of the nogauge index of said second mentioned remotely operable means into interposed position with the X-ray beam from said test source, to condition said thickness gauge for measuring the thickness of material passing through the X-ray beam form said test source by comparison with the thickness of the gauge members at the moment intercepting the X-ray beam from said standard source; and said selector means being operable t cause said control means to automatically operate said second mentioned remotely operable means and position the gauge members having the same total thickness as the gauge members at the same moment intercepting the X-ray beam from said standard source,v in the path of the X-ray beam from said test source for making a balance check of said thickness gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of the same thicknesses of said gauge members, and means operable at the will of an operator carried by said selector means and connected to said control means for causing the latter to automatically operate said second mentioned remotely operable means and increase by a. preselected amount the thickness Aof the gauge members interposed in the path of the X-ray beam from said test source with an attendant 26A registration of such .increased thickness as a further check on the accuracy of operation of said thickness gauge.

6. An X-ray thickness gauge for measuring material thickness comprising a "standard source of X-rays and a test source of X-rays, light sensitive means responsive to the intensity of the X-ray beam impinging thereon from said standard source and said test source and operable -to cause a registration of the intensity of the X-rays from said sources Ias a measure of material thicknesses when interposed in said X-ray beams, mechanism disposed adjacent the path of the X-ray beam from said standard source comprising independently rotatable discs provided with a plurality of gauge members of various known thicknesses ranging in hundredths and thousandths of an inch and movable into a position to intercept the X-ray beam from said "standard source, a second substantially identical mechanism disposed adjacent the path of the X-ray beam from said test source, also comprising independently rotatable discs provided with identical gauge members as said firstmentioned discs as well as having a no-gauge index and movable into a position -to intercept the X-ray beam from said test source, a remotely located `panel provided with selector knobs operable by an operator to preselect the particular gauge members interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular gauge members at the same moment interposed in the path of the X-ray beam from said test source, control ymeans operable by said selector knobs and electrically connected to both said mechanisms to cause automatic operation of the latter with attendant automatic rotation of the respective discs to position the gauge members of said firstmentioned mechanism having the desired thickness as preselected by said selector knobs in the path of the X-ray beam from said standard source and to automatically cause rotation of the no-gauge index of said second mentioned mechanism into interposed position with the X- ray beam from said test source, to condition said thickness gauge for measuring the thickness of unknown material interposed in the X-ray beam from said test source by comparison with the thickness of the gauge members at the moment intercepting the X-ray beam from said standard source; and certain of said -selector knobs being operable to also cause the said -control means to automatically operate said second mentioned mechanism with attendant rotation of its discs to position the gauge members having the same total thickness as the gauge members at the same moment intercepting the X-ray beam from said standard source, in the path of the X-ray beam from said test source for making a balance check of said thickness gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of the equal thicknesses of said gauge members.

7. An X-ray thickness gauge for measuring material thickness comprising a standard source of X-rays and a test source of X-rays, light sensitive means responsive to the intensity of the X-ray beam impinging thereon fromgsaid standard source and said test source and operable to cause a registration of the intensity of the X-rays from said sources as a measure of material thicknesses when interposed in said X-ray beams, mechanism disposed adjacent the .path of the X-ray beam. from said standard sourceV comprising independently rotatable discs provided with a plurality of gauge vmembers of various known thicknesses ranging in hundredths andthousandths of an inch and movable into a.

position to intercept the `X-ray beam from said "standard source, a second substantially identical mechanism disposed adjacent the path of source and to preselect the particular gauge mem-v bers at the same moment interposed in the path of the X-ray beam from said test source, control means operable by said selector knobs and electrically connected to both said mechanisms to cause automatic operation of the latter with attendant automatic rotation of the respective discs to position the gauge members of said I'irst-A mentioned mechanism having the desired thickness as preselected by said selector knobs in the path of the X-ray beam fromsaid standard source and to automatically cause rotation ofthe no-gauge index of said second-mentioned mechanism into interposed position with Athe X-ray beam from said test source, to condition said thickness gauge for measuring the thickness of unknown material interposed in the X-ray beam from said test source by comparison with the thicknessof the gauge members at the moment intercepting the X-ray beam from said standard source; and certain of said selector knobs being operable to also cause said control means to automatically operate said second mentioned mechanism with attendant rotation of its discs to position the 'gauge members having the same total thickness as Ithe gauge members at the same moment intercepting the X-ray beam from said standard source, in the path of the X-ray beam from said test source for making a `balance check vof said thickness gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of the equal thicknesses of said gauge members, and an additional selector knob on said panel operable at` the will of an operator and connected to said control means for causing the latter to automatically operate said second mentioned'mechanism with rotation of its discs to increase by a preselected denite amount the thickness of the gauge members interposed in the path of the X-ray beam from `said "test source with an attendant registration of such definite increased thickness as a further check on the accuracy of operation of said thickness gauge.

' 8."An X-ray thickness gauge for measuring material thickness comprising a standard source of X-rays and a test source of X-rays, light sensitive means responsive to the intensity of the X-ray beam impinging thereon from said standard source and said test source and operable to cause a registration of the intensity of the X-rays from said sources as a measure of material thicknesses when interposed in said X- Y. Y 2S l various known thicknesses ranging in hundredths of an inch for one of said discs and ranging in thousandths of an inch for the other of said discs, and one gaugemember of each disc being movable into a position to intercept the X-raybeam from said standard source; a second substantially identical mechanism disposed adjacent' the 'path of the X-ray beam from said test source also comprising independently rotatable discs provided with identical gauge members as said rst-mentioned discs as well as havinga no-I gauge index and onegauge member or the nogauge index of each disc being movable into a position to intercept the X-ray beam from said test source, a remotely disposed panel provided with a plurality of selector knobs operable by an operator to preselect theparticular gauge memi bers interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular gauge members at the same moment interposed in the path of the X-V ray beam from said test source, control means operable by said selector knobs and electrically connected to both said mechanisms to cause automatic operation of the latter with attendant automatic rotation of the respective discs to position the hundredths and thousandths gauge members of said first-mentioned mechanism having the desired thickness as selected by said selector knobs in the lpath of the X-ray beam from said standard source and to automatically cause rotation of the no-gauge index of the discs of saidA second-mentioned mechanism into interposed position with the X-ray beam from said test second mentioned mechanism with attendant rotation of its discs to position the gauge members having the same total thickness as the gauge' members at the same moment intercepting the X-ray beam from said standard source, in the path of the X-ray beam from said test source for. making a balance check of said thickness'A gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of the equal thicknesses of said gauge members, an additional selector knob on said panel operable at the Will of an operatorl and connected to said control means for causing the latter to automatically operate said second mentioned mechanism with rotation of its discs to increase by a preselected definite amount the thickness of the gauge mem-bers interposed in the path of the X-ray beam from said test source with an attendant registration of such definite increased thickness as a further check on the accuracy of operation of said thickness gauge,

and a still further of said selector knobs being" operable by an operator and connected to said control means and operable to cause the auto-v4 matic operation of both said mechanisms to `increase in steps of one-tenth of an inch the thickness of the gauge members interposed in the pathA of the X-ray beam from said standard and' test sources.

9. An X-ray thickness gauge for measuring material thickness comprising a source ofX-rays anda test source of X-rays; light sensitive means responsive tothe intensity standard-l 29 of the X-ray beam impinging thereon Yfrom said standard source and said "test source and operable to cause a registration of the intensity of the X-rays from said sources as a measure of material thickness when interposed in said X- ray beams, mechanism disposed adjacent the path of the X-ray beam from said standard source comprising independently rotatableV discs provided with a plurality of gauge members of various known thicknesses ranging in hundredths of an inch for one of said discs and ranging in thousandths of an inch for the other of said discs, and one gauge member of each disc Ibeing movable into a position to intercept the X-ray beam from said standard source; a second substantially identical mechanism disposed adjacent the path of the X-ray beam from said test source also comprising independently rotatable discs provided with identical gauge members as said first-mentioned discs as well as having a nogauge index, and one gauge member or the nogauge index of each disc being movable into a position to intercept the X-ray beam from said test source; a remotely disposed panel pro- .vided with a plurality of selector knobs operable by an operator to various preselected positions, a gang of tandem switches operable by the positioning of one of said selector knobs to preselect the particular hundredths gauge member interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular hundredths gauge member at the same moment interposed in the path of the X-ray beam from said test source, a second gang of tandem switches operable by the positioning of a second one of said selector knobs to preselect the particular thousandths gauge members interposed simultaneously with the hundredths gauge members in the path of the X-ray beam from the respective standard and test sources, electrical circuits connected to both said mechanisms and including certain of said tandem switches to cause operation of yboth said mechanisms with attendant automatic rotation of their respective discs to position the gauge members of said first-mentioned mechanism having the desired thickness as preselected by the positioning of said selector knobs, in the path of the X-ray beam from said standard source, and to automatically cause rotation of the no-gauge index of the discs of said second mentioned mechanism into interposed position with the X-ray beam from said test source, to condition said thickness gauge for measuring the thickness of unknown material interposed in the X-ray beam from said test source by comparison with `the thickness of the gauge members at the moment intercepting the X-ray beam from said standard source; another gang of tandem switches operable by the positioning of a further one of said selector knobs for closing certain of said electrical circuits to cause automatic operation of said second-mentioned mechanism with attendant rotation of its discs to position the hundredths and thousandths gauge members having the same total thickness as the gauge members at the same moment intercepting the X-ray lbeam from said standard source, in the path of the X-ray beam from said test source for making a balance check of said thickness gauge by a resultant null registration of the intensities oi the X-ray beam from both said sources as a measure of an equal thickness of said gauge members; and a still further gang of tandem switches operable by the positioning of a still further one of said selector knobs and included in certain other of said electrical circuits and operable to cause automatic rotation of the discs of said second-mentioned mechanism to increase by a preselected denite amount the thickness of the gauge members interposed in the path of the X-ray beam from said test source, with an attendant registration of such definite increased thickness as a further check on the accuracy of operation of said thickness gauge 10. An X-ray thickness gauge for measuring material thickness comprising a "standard source of X-rays and a test source of X-rays, light sensitive means responsive to the intensity of the X-ray beam impinging thereon from said standard source and said test source and operable to cause a registration of the intensity of the X-rays from said sources as a measure of material thickness when interposed in said X- ray beams, mechanism disposed adjacent the path of the X-ray beam from said standard source comprising independently rotatable discs provided with a plurality of gauge members of various known thicknesses ranging in hundredths of an inch for one of said discs and ranging in thousandths of an inch for the other of said discs, and one gauge member of each disc being movable into a position to intercept the X-ray beam from said standard source; a second substantially identical mechanism disposed adjacent the path of the X-ray beam from said test source also comprising independently rotatable discs provided with identical gauge members as said first-mentioned discs as well as having no-gauge index, and one gauge mem-ber or the no-gauge index of each disc being movable into a position to intercept the X-ray -beam from said "test source; a remotely disposed Ipanel provided with a plurality of selector knobs operable by an operator to various preselected positions, a gang of tandem switches operable by thev positionng of one of said selector knobs to preselect the particular hundredths gauge member interposed at a given moment in the path of the X-ray beam from said standard source and to preselect the particular hundredths gauge member at the same moment interposed in the path of the X-ray beam from said test source, a second gang of tandem switches operable by the positioning of a second one of said selector knobs to preselect the particular thousandths gauge member interposed simultaneously with the hundredths gauge members in the path of the X-ray beam from the respective standard and test sources, electrical circuit connected to both said mechanisms and including certain of said tandem switches to cause operation of both said mechanisms with attendant automatic rotation of the respective discs to position the gauge members of said iirst-mentioned mechanism having the desired thickness as preselected by the positioning of said selector knobs, in the path of the X-ray beam from said standard source, and to automatically cause rotation of the nogauge index of the discs of said second mentioned mechanism into interposed position with the X-ray beam from said test source, to condition said thickness gauge for measuring the thickness of unknown material interposed in the X-ray beam from said test source by comparison with the thickness of the gauge members at the moment intercepting the X-ray beam from said "standard source; another gang of tandem switches operable by the positioning of a further one of said selector knobs for closing certain 3l of said electrical circuits to cause automatic operation of said second-mentioned mechanism with attendant rotation of its discs to position the hundredths and thousandths gauge members having the same total thickness as the gauge members at the same moment intercepting the X-ray beam from said standard source, in the path of the X-ray beam from said test source for making a balance check of said thickness gauge by a resultant null registration of the intensities of the X-ray beam from both said sources as a measure of an equal thickness of said gauge mem-bers, a further gang of tandem switches operable by the positioningl of astill further one of said selector knobs and included in certain other of said electrical circuits and automatically operable to cause rotation' of the discs of said second mentioned mechanism to increase by a preselected denite amount the thickness of the gauge members interposed in the path of the X-ray beam from said test source with an attendant registration of such denite increased thickness as a further check on the accuracy of operation of said thickness gauge, and a still further gang of tandem switches operable by' the positioning of another one of said selector knobs and included in still additional of said electrical circuits and operable to automatically increase in steps of one-tenth of an inch the thickness of the gauge members interposed by both said mechanisms in the path of the X- ray beam from said standard and test" sources. Y

WALTER N. LUND'AHL.

REFERENCES CITED The following references are of record in the le of this patent:

lClapp et al.: Electrical Engineering, May 1948, pp. 441-444. 

